DE2728979C2 - Non-tacky moldings and processes for their manufacture - Google Patents

Description

3% by weight of water soluble material and less than 1% by weight of volatile material, also optionally customary additives and 0.05 to 3% by weight of a coherent material uniform porous coating of a water-insoluble, water-containing inorganic Oxide from the silicic acid and aluminumic acid polymers, Silicic acid-aluminum acid copolymers and their mixtures exist, the molded parts having a smallest dimension of 0.01 to 10 mm. Is under a "uniform" cover a coherent, uniform covering as opposed to one consisting of discrete particles Coating, e.g. B. a powder coating to understand. Under the "smallest dimension" is the diameter of the To understand the smallest round hole through which the molded part passes in the longitudinal direction

A unique feature of the invention is that the non-sticky molded parts before Removal of the water-soluble and volatile substances are extremely porous. This porosity can be recognized by that the molded parts appear opaque when dispersed in water and that their transverse step area shows a bubble structure on microscopic photographs and volatiles can be easily removed by washing and drying. The porosity remains even after Washing and drying partially preserved.

The non-sticky, elastomeric molded parts according to the invention are produced by a process which is characterized in that a latex of a normally sticky, non-crosslinked one Elastomers with a solids content of 20 to 65% by weight in the form of drops or a regulated Brings the stream into contact with an aqueous bath which, based on the total weight of the bath,

a) 0.15 to 25% by weight of a soluble coagulating salt for the latex and

b) 0.01 to 5% by weight of a soluble or colloidally dispersed one, water-containing inorganic oxide from the silicic acid polymerizate, aluminum acid polymerizate, Silicic acid-aluminum acid copolymers or mixtures thereof existing group

contains and a pH of ?. to 7, so that when a drop of 1.0 n —NaOH is added to the bath, the drop is immediately surrounded by a cloudy coating of water-containing inorganic oxide Latex coagulates and forms highly poious molded parts of the coagulated elastomer that are coated with the water-insoluble, water-containing inorganic oxide, so that the molded parts formed are separated off and water-soluble and volatile substances are removed from them. The latter can consist in the fact that the molded parts can then be washed with water until the content of water-soluble material is less than 3% by weight, after which they can be dried until the content of volatile substances is less than 1% by weight. %, free-flowing, free-flowing, non-sticky elastomeric molded parts being obtained. The invention is particularly suitable for the production of non-sticky pellets or non-sticky granules of unvulcanized polychloroprene (neoprene).

The term "molded body" as used here denotes the latex before it enters the aqueous bath Brought into contact. The term "molded part" used here is used to denote the latex and of the subsequent elastomer after the molding has been introduced into the bath.

The invention is described below with reference to the figures.

F i g. 1 shows a preferred device as a central vertical section and partly as a side view for performing an embodiment of the method .according to the invention. This device and that Process in which this device is used are the subject of DE-OS 27 29 056 of the applicant. F i g. 2 shows from above the in FIG. 1 along the section line 2-2.

F i g. 3 is an illustration of a micrograph of the cross-sectional area of a porous molded article according to FIG the invention.

According to the invention, a coating of an inorganic oxide polymer is chemically deposited on a molded part made of a normally sticky elastomer from a solution or dispersion in an aqueous bath. The ^coating: therefore st as it is formed has a porous, non-particulate, sealed surface, each mold part completely surrounds Due to the uniform, continuous nature of the top coating can be non-sticky molding parts with very low loadings of the coating material are obtained. This is particularly important for elastomers that are later dissolved before vulcanization or crosslinking, and is in sharp contrast to the heavy load required with finely divided substances, e.g. B. talc, previously used to make unvulcanized elastomeric moldings non-sticky. The products according to the invention are non-sticky molded parts of normally sticky, unvulcanized elastomers. The term “elastomer” is familiar to the person skilled in the art and is defined in publications such as “ASTM Glossery of Terms Relating to Rubber and Rubber Like Materials”, page 38. A "normally sticky elastomer" is understood to mean an elastomer of which two pieces stick together in the unvulcanized and largely decrystallized state at room temperature. Suitable elastomers for the purposes of the invention are homopolymers and copolymers of conjugated dienes, e.g. B. polychloroprene and natural rubber, copolymers of conjugated dienes with other polymerizable organic monomers, ζ. B. butadiene-acrylonitrile copolymers and butadiene-styrene copolymers, elastomeric fluoropolymers (fluorine-containing polymers), preferably copolymers of vinylidene fluoride and at least one other fluorine-containing monomers, ζ. Β. Copolymers of vinylidene fluoride and hexafluoropropene (US-PS 30 51 677) and terpolymers of tetrafluoroethylene, vinylidene fluoride and hexafluoropropene (US-PS 29 68 64S), elastomers of the adhesive type, e.g. B. polyvinyl acetate and ethylene-vinyl acetate CopoIymerisate, acrylate rubbers, z. B. the polymers of lower alkyl acrylates, hydrocarbon elastomers, z. B. polyisobutylene, the terpolymers of ethylene, propylene and non-conjugated dienes, and similar materials.

The preferred elastomer is polychloroprene. "Polychloroprene" means elastomers that Contain at least 50% ChloroDren (2-chloro-13-butadiene). As examples of representative comonomers that can be used with chloroprene, include: Vinyl aromatic compounds, e.g. B. styrene, the

Vinyl toluenes and vinyl naphthalenes. aliphatic conjugated Diolefin compounds, ζ. Β. 13-butadiene, isoprene, 2,3-dimethyl-l 3-butadiene and 2,3-dichloro-1,3-butadiene, Vinyl ethers, esters and ketones, e.g. B. methyl vinyl ether, vinyl acetate and methyl vinyl ketone, esters, amines and nitriles of acrylic acid and methacrylic acid, e.g. B. ethyl acrylate, methyl methacrylate, methacrylamide and acrylonitrile.

Polychloroprene latices for the purposes of the invention can be obtained by the known polymerization of chloroprene in aqueous emulsion using sodium rosinate as a dispersant and a free radical forming catalyst, e.g. B. potassium persulfate. Sodium rosinate used as a dispersant can be prepared in situ from resin acids and sodium hydroxide.

Additives, e.g. B. fillers, antioxidants and the like. may be present during the polymerization. The polymerization is allowed to go up to a predetermined one Degree of completion take place, after which a catalyst deactivating agent are added can and residual monomeric chloroprene is removed. Slight variations in the way of working result Latices of polymers, which in molecular weight, in viscosity, crystallinity and in others Properties are different. For the formation of granules or pellets in the method according to the invention the latex must have a solids content of at least 20% by weight. Latices with solids contents are suitable up to 65%. The latices generally coagulate when the solids content exceeds 65%. Preferably the latex has a solids content of 35% to 50%.

The invention encompasses the method of adding drops, a metered stream, or any other distributed form of a latex of the normally sticky elastomer to form an aqueous coagulating agent and coating bath in which molded parts coated thereby are formed. The latex emulsion must be sufficient Have resistance so as not to break during the course of the addition, until the molded parts from coagulating Salt and any neutralizing agent present are completely permeated. Polychloroprene latices are normally stabilized against premature coagulation by sodium rosinate, while natural rubber latices are stabilized by ammonia.

The aqueous coagulation and coating bath used contains a coagulation salt for the latex, d. H. a salt that coagulates the elastomer latex. Suitable coagulation salts are known to the person skilled in the art and are for example in "Neoprene Latex" by J. C. Carl, pp. 19-21, edited by the applicant, described. For example, the water-soluble sulfates, chlorides, bromides, nitrates, citrates, Acetates, formates and phosphates of ammonium, sodium, potassium, calcium, magnesium, strontium, barium, Lithium, beryllium, aluminum, manganese, zinc, yttrium, iron and caomium. Mixtures of these salts can also be used.

Desirable but not limited to the following properties of the coagulating salt: Es should be cheap, form colorless solutions, contain cations and anions that are not easily oxidized or reducible are not precipitated with the alkali salt that accumulates in the bathroom, non-toxic and non-polluting be. Preferably the salt should be chemically inert to and insoluble in the elastomer be. Preferred salts are soluble chlorides, sulfates, acetates, nitrates and phosphates of sodium, potassium, Ammonium, calcium, magnesium and aluminum. The soluble salts are particularly preferred as salts Chlorides and sulphates of the abovementioned catalysts. The coagulating salt can contain 0.5 to 25% by weight of the Turn off the bath. The appropriate amount of the coagulating salt within this range in any given The case depends on the particular latex, the pH of the bath and the particular inorganic present

ίο Oxyd off. In general, it is the optimal and preferred one Amount of salt in the range from 1% to 10%.

The bath also contains a soluble or colloidally dispersed, water-containing inorganic oxide that of silicic acid polymers, aluminum acid copolymers, silicic acid-aluminum acid copolymers or mixtures of these polymers. These are oxides according to It is generally believed to be in polymeric form and have a structure made up of linear chains, bands or, if they are strongly cross-linked, even consist of balls in which the atoms of the inorganic element alternate with oxygen atoms. In these polymers some of the peripheral groups are -OH groups.

The inorganic oxide can be in water-soluble form, as is the case with polysilicic acid and Polyaluminic acid is the case, or in a more polymerized, finely divided form, as is the case with colloidally dispersible silica sols.

as described in US-PS 25 74 902, and Alumina sols, as described in US Pat. No. 2,590,833, is the case. In practice lies with the Most aqueous systems containing these compounds contain at least some of the polymeric oxide in Form of dispersed particles. The terms "silicic acid polymers" and "aluminum acid polymers" include these polymers both in the soluble and in the koiioidai dispersible form. The inorganic Oxides can be in crystalline or amorphous form. Also mixtures of two or several of these oxides can be used. Polysilicic acids are particularly preferred as inorganic oxides. Polyaluminic acid and silica-aluminum acid copolymers.

If the coagulating salt used is an aluminum salt and the inorganic oxide is polysilicic acid some of the hydroxyl groups generated on the alkaline surface of the latex may be of aluminum acid by condensation with silanol groups with formation

copolymerize such an aluminum acid-silica copolymer. When the Koagu ¹ used irungssalz 'no aluminum salt, especially when using Polykieseisäure as wrapping material in the bath, it is convenient, although not essential, to add to the bath from 0.002 to 2 wt .-% of an ionizable salt of aluminum. The copolymerization of aluminum has not yet been clearly demonstrated, but it is believed that this is the explanation for the fact that the inorganic oxide is made more effective as a coating, possibly due to the reduction in any subsequent solubility of the coating in the wash water. It has been shown that yttrium salts are equivalent to the aluminum salts for this purpose and are wholly or partly as a substitute

fc> can be used for this. The expression "silica-aluminum acid copolymer" is accordingly to be interpreted in the claims so that this use of equivalent salts instead of the

Includes aluminum salts.

It is generally accepted that the silica in freshly prepared silica solutions is not monomeric but has a molecular weight of the order of about 1000. During the aging of the Silica solution, the molecular weight continues to rise until the solution finally gels (see Bechtold, J. Phys. C'hcni. 59 (1955) 5J2-54I). For the purposes of the invention The silica solution used should not have aged more than 90% of its gel time before it Bath is added. Preferably, the silica solution has aged 5 to 70% of its gel time before it Bath is added. With continuous operation, silica is continuously added to and from the bath Bath withdrawn, whereby the average age of the polysilicic acid reaches a constant value, which is lower is than their gel time.

The hydrous inorganic oxide can constitute from 0.01 to 5% by weight of the coagulating bath. The presence more than ½ of the inorganic oxide does not result in any further improvement in non-tackiness of the product. Preferably the inorganic oxide is present in an amount of from 0.03 to 2 percent. The oxide can be polymerized or crystallized during the coating process. A clue that when a bath for the method according to the invention is no longer suitable, is the coagulation of the Bath as a result of changed conditions such as pH value or depletion of essential components.

The bath can optionally also contain a small amount of a surfactant, the the interfacial tension between air and liquid is reduced and the penetration of the molded Latex body supports in the bathroom. Suitable surface-active compounds are characterized by that they are effective and tolerable in low concentrations; d. H. no polymerisation or cross-linking

j u_u: s \ ι- ι: _i ι j_o _: -

£ utig UC3 waaaci immgcn vyAjrua ucwun.cu, unu Udu »ic are inert to the coagulating salt. A wide variety of nonionic, anionic, cationic and amphoteric surfactants can be used. Lower alkyl alcohols, for example, are suitable. z. B. Ethanol, the trimethylnonanol ether of ethylene oxide, sodium heptadecyl sulfate, sodium laurysulfate, the condensation products of tertiary amines with ethylene oxide and fluorinated amphoteric surfactants. The surfactant is preferably added in an amount which is sufficient to reduce the interfacial tension between air and liquid to less than 50 dynes / cm, in particular to less than 35 dynes / cm.

The bath can be used at a pH in the range 2 to 7. When the pH is below 2, the inorganic oxide is difficult to gel on the surface of the molding. If the pH is above 7, conversion of the inorganic oxide to a soluble salt can take place. The appropriate pH within this range for any given system will depend on the particular latex, coagulation salt, and inorganic oxide present. Within this range, pH values from 2.5 to 5.5 are particularly preferred in order to achieve an optimal balance between bath stability and effectiveness of the coating the life of the bath can be extended significantly. Organic and inorganic acids, e.g. B. acetic acid, and aqueous hydrochloric acid, and hydrolyzable acid salts, e.g. B. AlCh, are particularly suitable neutralizing agents.
The suitability of the bath for forming a coating on the molded parts depends on the amount and type of hydrous inorganic oxide present and on the pH of the bath. It has been found that not all combinations of the above variables result in suitable baths. The requirements that must be met by a functional bathroom have not yet been fully clarified, but a simple test has been found that can determine whether the bathroom is suitable. In this test, one drop of 1.0N sodium hydroxide is added to the bath.

If the drop is immediately surrounded by a cloudy coating of gelled hydrous oxide, is suitable for the bathroom.

The pH of different latices can be within vary further limits, but the pH of the latex should preferably be as high or higher than the pH of the bath. In the case of a chloroprene latex, which contains sodium rosinate as a stabilizer, the pH value lies of latex over 7 if it has not been acidified.

When the latex is added in the form of drops, the precipitated moldings can take the form of lumps, Have pearls, pellets (with or without a "tail"), discs or rings. This depends on the surface tension and the density of the precipitation bath and the speed and direction of the latex on entry into the bathroom. When the latex is added as a regulated flow, the flow can be filamentary, wherein a precipitated fiber or strand is obtained, or the stream can be spread out in flat or curved form forming a precipitate in the form of a tape, sheet or tube. Drops and regulated currents can be added to the bath either from above or below the surface will. The latex is preferably added to the bath from above in the form of drops.

The entry of the latex into the bath and the movement of the precipitated, encased molded parts through the bath cause some movement of the bath. An additional movement by stirring or shaking can optionally be done to promote the evenness of the bath. A bath movement is particularly desirable when the pH is controlled by the addition of acid in the manner described above will.

The method of the invention can be carried out at temperatures ranging from 0 ° to about 100 ⁰ C. Temperatures in the range of 5 ° to 70 ⁰ C with a range of 10 ° to 40 ° C due to the improved stability of the bath is particularly preferably in this range are preferred.

The pressure is not a critically important variable in the method according to the invention. The procedure can be carried out at elevated and reduced pressure. For the sake of simplicity, normal pressure is used preferred

The time from the entry of a given elastomeric latex body into the bath to the removal of the nontacky ones elastomeric moldings from the bathroom can be within wide limits and depends to a certain extent from the smallest dimension of the molded part to be encased away. The time can vary between 0.5 seconds and 6 hours or more. Upon contact with the Bath, the latex begins to coagulate, and a non-small

ίο

The rest of the coating is immediately, ζ. B. within 0.5 to 5 seconds, on the surface of the coagulated molding educated. Longer dwell times of the enveloped molding in the bath are chosen if complete Coagulation and neutralization of the latex in the middle of the encased molding before it is removed desired in the bathroom. In the preferred baths, this takes less than 6 minutes. Complete coagulation in the bathroom is not essential, since a coagulant that has penetrated into the molded article is removed after the molded article is taken out the bath can continue to migrate to the center of the molding. However, the moldings are preferably in the Hold bath until enough coagulant has penetrated to complete coagulation.

A preferred embodiment of a suitable apparatus for carrying out the method according to The invention is shown in FIG. This apparatus has a cylindrical container 11 (27.94 cm inner diameter) and a cylindrical suction tube 12 (12.7 cm inside diameter) arranged concentrically to the container 11 on. The tube and the container can be made of any rigid material, e.g. B. glass, metal or plastic. The suction tube 12 is extended at the upper end by a wire screen 13, the Meshes are smaller than the size of the molded parts to be produced. The liquid level of the bath 14 that the polymeric inorganic oxide and the coagulating salt is maintained at such a level that the surface 15 of the bath is slightly below the upper edge of the sieve 13. Drops or discrete masses of the Polymer latex are introduced into the bath within the zone surrounded by the sieve 13. In this embodiment capillary tubes 16 (19 mm long, 0.86 mm inside diameter, 13 mm outside diameter) made of stainless steel used to form the latex droplets. These pipes are made with plugs Poiytetrafiuoräthyien in a plate of stainless Steel used, which is screwed to the lower end of the tube 17 (101 mm inner diameter). The distance between the tubes attached to the plate from center to center is 11.1 mm. 61 pipes are in Hexagon with 5 tubes arranged on one side. The frequency of adding drops to the bath will be adjusted by changing the height of the latex in the pipe 17.

A stirrer 18 is arranged in the bottom of the container 11, to direct the circulation of the bath so that the bath solution generally down through the suction tube after through the space between the suction tube and the wall of the container and through the sieve to the top Surface of the enclosed bath flows for this purpose a three-bladed boat propeller (152.4 mm diameter) was used

The sieve at the upper end of the suction tube allows a solution that is free of moldings to enter the upper one Introduce the end of the suction tube. It also stops and contributes to the foam created by the stirring help to keep the surface free from disturbances affecting the evenness of the falling through the surface Could affect molded parts. To increase the movement and thereby the suspension of the enveloped To accelerate latex particles in the annulus outside of the suction pipe, baffles 19 (38.1 mm wide) arranged vertically along the walls of the container 11 at intervals of 90 ° not always necessary depending on the type of bath movement used.

The shaped bodies come through the action of the suction pipe, the sieve, the stirrer and baffles in contact with fresh solution free of coated particles and foam. The moldings stay on their way down through the suction tube discreetly and separately. At the time when they come out of the intake manifold emerge, they are encased so that the tendency to agglomerate with previously encased molded parts is eliminated is. The encased moldings are then kept in suspension outside of the suction tube until they removed from the bathroom.

A typical batch test can be carried out using this apparatus as follows: First, a Bath 14 consists of an aqueous solution of an inorganic salt, a small amount of a surface-active one Connection and the wrapping material made. The salt serves to coagulate the latex during the Wrapping and after wrapping. The surface-active Medium facilitates the passage of latex plugs through the surface of the bath.

The latex is placed in the standpipe 17 to reduce a given pressure of the liquid column and then added continuously to maintain this pressure of the liquid on the capillary tubes. Since no solution is withdrawn from the bath during the experiment, the liquid level in the bath rises as a result of the addition of the latex. The standpipe 17 and the suction pipe 12 are arranged so that they can be moved vertically. In the course of each experiment they are moved so that the exits of the capillary tubes remain 25.4 mm above the bath surface 15 and the upper edge of the sieve 13 remains 835 mm above the bath surface 15.
The apparatus shown in the figures allows only the batch removal of coated molded parts at the end of each operating period, but the process can also be carried out continuously by arranging an overflow pipe in the container 11 for the continuous removal of coagulated coated molded parts from the bath The suspension of the molded parts flowing through the overflow pipe is filtered, the filtrate is returned to the bath and the components of the bath are replaced as they are used up.

A main advantage of the invention is that the uncrosslinked moldings do not agglomerate when they are stored in contact with each other under ordinary conditions but are easily separable and remain free-flowing. The molded parts have a smallest dimension of 0.01 to 10 mm. The smallest dimension should be at least 0.01 mm to avoid dust formation. Molded parts with the smallest dimension of more than 10 mm require an excessive expenditure of energy for mixing with other mixing additives for practical use. The molded parts preferably have the smallest dimensions from 0.1 to 5 mm.

Since the molded bodies introduced into the bath are made of latex, the water-soluble coagulating salt penetrates quickly enters the aqueous phase of the moldings, causing the latex with minimal internal confluence This has the consequence that the coagulated elastomer within the non-tacky coating during remains sufficiently porous for a sufficient period of time,

f5 to the water-soluble components including the To wash out coagulating salt, in the case of proportionate This porosity is retained indefinitely in crystalline elastomers. In the case of relaüv non-critical

stable elastomers, ζ. B. polychloroprene, the porosity less if left to stand for a long time, but it does not disappear completely.

After the precipitated moldings have been coagulated and enveloped, they can be used in any suitable Way to be separated from the bathroom. It is advisable to remove water-soluble and volatile substances from the molded parts after they have been disconnected from the bath. This can be done by washing with water or a polar organic solvent and then squeezing, centrifuging or drying according to the usual Procedure can be achieved. The moldings should be washed until they are less than 3% by weight, preferably contain less than 1% water soluble material.

After the water-soluble material has been removed to the desired extent, the molded parts are dried in order to remove volatile substances. The drying may be at air temperatures of 25 ° to 250 ° C carried out feed and wiid preferably uci Limtemperaturen of 100 ° to 135 ⁰ C made. While this *. During drying, the temperature of the molded parts is kept below the known temperature of the thermal decomposition of the polymer. The molded parts are dried until they contain less than 1% by weight, preferably less than 0.5% by weight, of volatile substances.

During these final treatments, polymers remain that are relatively stiff (for example by Kristalünitü), opaque and porous, while normally sticky polymers continue blend together until they are translucent. Nevertheless, these polymers also retain traces its previously highly porous structure, and the non-sticky nature of the hydrous oxide The coating on its surface remains unbroken. This non-sticky coating can be given

Talc can be added during the final stages of drying at high temperature.

The non-sticky coating on the normally sticky elastomer is initially also porous, so that moisture, solvent, soluble components of the reaction mixture and by-products easily can be removed from the interior of the encased molded parts. The coating can contain 0.05 to 3% by weight of the make out covered molding. Less than 0.05% will generally not provide sufficient tackiness achieved, while with more than 3% generally no additional benefit that offsets the increased costs, is achieved. The covering preferably makes up 0.5 to 2% by weight of the covered molding. the Wash treatments as described above emphasize the need for both the non-tacky coating as well as the coagulated elastomer for a period of time after formation the molded parts are porous.

F i g. 3 is a reproduction of a photomicrograph of a cross section of a typical porous molding according to the invention. In this representation, the porosity of the molded part can be clearly seen. The pores and Voids appear as dark areas at 20, while the non-tacky coating clearly appears as light areas at 21 can be seen.

The non-sticky coated molded parts according to the invention can also contain fillers, pigments, dyes, Plasticizers, extenders, antioxidants. Stabilizers, crosslinking and vulcanizing agents and the like included. These materials can be incorporated by replacing the original polymer latex or added to the coagulation and coating bath.

The manufacture of non-tacky elastomeric moldings in accordance with the invention is illustrated in the following Examples described.

The washed and dried, non-tacky elastomeric moldings produced in these experiments contained less than 3% by weight of water-soluble material and less than 1% of volatiles. In each case, the coating of the polymeric inorganic oxide made 0.05 to 3 wt .-% of the moldings, and the smallest dimension of the mold parts was 0.01 to \ f> 10 mm. All quantities and percentages in the examples are based on weight.

The polychloroprene latices. the ones in this. Experiments described in the examples were used, were made as follows:

Polychloroprene latex No. 1

This latex was prepared from an aqueous alkaline emulsion containing 100 parts of chloroprene and 0.23 part of dodecyl mercaptan as modifying agent and stabilized with 2.9 parts of the sodium salt of disproportionated rosin. The chloroprene was polymerized by adjusting the temperature of the emulsion to 40 ° C and _{continuously adding an aqueous solution containing 03% K 2} S ₂ O ₈ and 0.015% of the sodium salt of anthraquinone-ß-sulfonic acid at such a rate, that the temperature could be kept at 40 ° C by external cooling. The polymerization was at a conversion of 67% of the monomeric chloroprene by adding an aqueous emulsion of a toluene solution containing 0.015 part of phenothiazine, and 0,015 parts of 4-t-But ^v! Catechir! contained, ended.

After the residual monomer was distilled off, the latex contained 37% solids. The polymer had an inherent viscosity of 1.20 (0.1 g / 100 ml benzene at 30 ° C). The latex had a pH of 12.

Polychloroprene latex No. 2

An aqueous alkaline emulsion containing 100 parts of chloroprene, 0.15 parts of dodecyl mercaptan and 3.5 parts of the Disproportionated rosin sodium salt was prepared. The chloroprene was polymerized, by adjusting the temperature of the emulsion to 10 ° C and an aqueous dispersion containing 1.0% K2S2O8,0.05% of the sodium salt of anthraquinone-ßsulfonic acid and containing 0.14% cumene hydroperoxide was added continuously at such a rate was that the temperature could be kept between 10 ° and 20 ° C. The polymerization was at a conversion of 85% of the monomeric chloroprene by adding an aqueous emulsion of a toluene solution terminated by 0.03 part of phenothiazine and 0.03 part of 4-t-butylcatechol

After removing the remaining monomer, the emulsion was 37% solids. Its pH was 12.5.

Polychloroprene latex No. 3

This latex was made in the same way as polychloroprene latex No. 1, but with one Mixture of 92 parts of chloroprene and 8 parts of 23-di-

chloro-13-butadiene was used in place of 100 parts of chloroprene. The polymerization was at a Sales canceled by 65%. After distilling off the remaining monomer, the latex contained about 33% solids and had a pH of IZ

Polychloroprene latex No. 4

This latex was prepared in the same manner as the polychloroprene latex No. 2 except that the amount of the dodecyl mercaptan in the Emulsion of the monomer was 0.12 part instead of 0.15 part. The latex obtained had a solids content of 37% and a pH of 12.5.

example 1

Egg ₁ -I bath, which contained 0.7% SiO ₂ and 3, 5% Ca (NOj) ₂ , was prepared by adding 90 ml of 0.25 molar aqueous silica (prepared by ion exchange of H ⁺ for Na ⁺ in 0 , 25 molar sodium metasilicate solution), 10 ml of a 50% aqueous Ca (NOa) ₂ solution and 100 ml of absolute ethanol. 20 ml of polychloroprene latex No. 1 (37% solids, pH 12) were added dropwise to this bath from a nozzle arranged 2 cm above the surface of the drops. sticky coating. The opaque pellets obtained were lifted out of the bath and ^{dried in a heating cabinet kept at 60 °} C. At room temperature, they remained dry to the touch and free-flowing and free-flowing.

For comparison, the following experiment, outside the scope of the invention, was carried out: The experiment described above was repeated using 90 ml of water in place of the silica solution. The drops of the emulsion coagulated quickly, but after drying at 60 ^° C. remained very sticky and difficult to separate.

Example 2

A bath containing 3.6% SiO ₂ and 2.6% CaCl ₂ was made by mixing 1000 ml of 1 molar silica, 60 ml of a 50% CaCl ₂ solution, 700 ml of absolute ethanol and 240 ml of distilled water manufactured. 200 ml of the No. 1 polychloroprene latex (37% solids, pH 12) was added dropwise to the bath. The resulting pellets were kept in the bath for 30 minutes. They were removed, washed with 70% ethanol, and dried for 48 hours in a vacuum drying gun heated by refluxing acetone. The pellets obtained had the following analytical values; 0.25% Ca, 0.38% Na, 0 ^ 1% Si, 2.8% ash. The pellets produced in this way retained a small amount of alkali. These amounts of the remaining alkali stabilize the polychloroprene against degradation by HCI. A 5% suspension of these pellets in water had a pH of 9.0. The pellets were more than 90% soluble in toluene, indicating that little or no crosslinking of the polychloroprene had occurred.

14th Example 3

An alcohol-free bath containing 1.5% SiO ₂ and 2.1% CaCl ₂ was diluted using a aqueous solution of a nonionic surfactant which the Reduced interfacial tension at the interface between air and liquid, prepared A mixture of 10 ml of freshly prepared 0.5 molar silica, 9.4 ml of 0.2% aqueous trimethylnonano- Lethers of hexa (ethylene oxide) glycol made by reacting 6 moles of ethylene oxide with 1 mole of trimethylnonanol and 0.6 ml of 50% CaCl ₂ completed the bath. 2 ml of the No. 1 polychloroprene latex (37% solids, pH 12) added dropwise to the bath formed opaque non-sticky pellets. The pellets were isolated, washed with water and air-dried to give free-flowing, non-sticky pellets 3 to 4 mm in diameter. The moisture content of the pellets was 038%, the ash residue 3.05%. The analysis showed 044% C 025% N d%

Example 4

A bath containing about 1.5% SiO ₂ and 2.1% CaCl ₂ was made from 1000 ml of 0.5 molar silica (pH 33), 940 ml of the 0.2% aqueous trimethylnonanol ether mentioned in Example 3 and 60 ml a 50% aq . engined CaCl ₂ solution prepared The initial pH value was of the bath 4,45.100 ml polychloroprene # 1 (37% solids, pH 12) was added dropwise over 10 minutes During this time, stirring the bath and the pH through continuous Addition of 1.0N hydrochloric acid kept at 4.0. The bathroom showed no evidence of gel formation. The polychloroprene pellets formed were taken from the bath on a Filtered off 149 μ stainless steel sieve, washed with cold water and dried. They were non-sticky and free flowing.

Example 5

A silica solution was prepared from a sodium silicate _{solution with an SiO 2} / Na ₂ O ratio of 135. The sodium silicate solution used had quality 6 (manufactured by the applicant), ie a viscosity of 60,000 oCPs (at 68 ° C.), a specific one Weight of 1.708. an Na ₂ O content of 18.4% and an SiO ₂ gel of 36.0%. This solution (166.5 ml) was diluted to 2 L with distilled water. The resulting solution was passed through a cation exchange column containing 1300 g of cation exchange resin passed in the acid form. The first 500 ml of the effluent, which corresponded to the retention volume of the column were discarded. The rest of the process was caught.

A portion of 1000 ml of this 0.85 molar silica

solution was used in the experiment described in Example 4, a bath containing about 2.5% SiO ₂ being obtained. At the beginning of the addition of the polychloroprene latex, the bath had a pH value of 3.1 and at the end of the addition a pH value of 4.1. the obtained pellets were washed with distilled water and dried. They showed little inclination to agglomeration.

6th 27 28 979 16 10 15th example example

A bath containing 1.4% SiO ₂ and 7.6% NaCl was prepared from 15 ml of 10% strength aqueous NaCl and 5 ml of 1.0 molar aqueous silica % Vinyl acetate and 82% ethylene were added dropwise to the bath. The drops coagulated to form pellets, which were filtered off from the bath, ^{dried under reduced pressure at 80 °} C., washed with water to remove all traces of NaCl and dried again. The product was non-sticky and free flowing.

For comparison, the following tests, which do not fall within the scope of the invention, were carried out: The experiment described above was repeated twice, with water instead of the in the first case NaCl solution and in the second case water was used instead of the silica solution. In both cases the drops were too brittle to be taken out of the bathroom unharmed.

Example 7

A solution which contained 1.4% SiO ₂ and 6.1% NaCl was made by adding 262 ml of 1N HCl, 14.7 g of NaCl and 38 ml of H ₂ O to 100 ml of 1 molar Na ₂ SiO ₃ · 9 H ₂ O produced with rapid stirring. At 0 ^° C., 20 drops of the vinyl acetate-ethylene copolymer latex described in Example 6 were added to this solution. After 10 minutes, the pellets formed were removed from the bath and ^{dried in a vacuum oven at 80 °} C. for 2 hours. The pellets were encased in a non-sticky coating and were free-flowing and pourable.

Example 8

About 200 ml of a natural rubber latex containing 62% solids was added dropwise to a bath containing 0.9% SiO ₂ and 2.5% CaCl ₂ and made up of 250 ml of 1 molar silica, 1750 ml of absolute ethanol and 60 ml of 50% strength aqueous CaCl ₂ had been produced. The latex coagulated quickly, with a non-tacky coating forming on the surface of the particles. After isolation and drying, the pellets were non-sticky and pourable.

Example 9

Carbon black was mixed with No. 1 polychloroprene latex (37% solids, pH 12) in an amount such that a uniform emulsion containing 4% carbon black based on the polychloroprene was obtained. 20 ml of this modified latex was added dropwise to a bath containing 1.5% SiO ₂ and 2.1% CaCl ₂ and made of 100 ml of 0.5 molar aqueous silica. 94 ml of the 0.2% strength aqueous trimethylnonanol ether mentioned in Example 3 and 6 ml of 50% strength aqueous CaCl ₂ had been prepared. The drops were added from a Pasteur pipette near the surface of the bath while the bath was being stirred with a magnetic bar. After 30 minutes in the bath, the pellets formed were separated off by decanting, washed three times with 500 ml of water each time and air-dried. The soot-containing pellets were non-sticky and free-flowing.

The experiment described in Example 9 was repeated, except that 10% finely ground aluminum was used instead of 4% carbon black in the latex. Non-sticky, pourable. Pellets containing aluminum were obtained.

Example 11

The experiment described in Example 9 was repeated, but with 10% aluminum oxide trihydrate (Powder, fired at 135 to 195 ° C) instead of 4% carbon black was used in the latex. Non-sticky, free flowing pellets containing alumina were obtained.

Example 12

The experiment described in Example 9 was repeated, but with 10% magnetic iron oxide (Fe3O4) were used instead of 4% carbon black in the latex. Non-sticky, free-flowing, containing iron oxide Pellets that could be moved easily with magnets, were received.

Example 13

100 ml of a 65% solids latex of an elastomeric fluoropolymer made from 45% vinylidene fluoride, 30% hexafluoropropylene and 25% tetrafluoroethylene were added dropwise to a bath made from 500 ml of 0.5 molar aqueous silica saturated _{with BaCl 2,} 500 ml of water which was _{saturated with BaCl 2} and 2 ml of the 2% strength aqueous trimethylnonanol ether mentioned in Example 3 had been prepared. The drops flattened out on contact with the bath, but coagulated completely and were encased in a non-sticky coating. The particles were decanted from the bath, washed several times with water and air-dried to give white, free-flowing flakes with a diameter of 5 mm.

Example 14

A mixture was made up of equal volume parts of the No. I polychloroprene latex (37% solids, pH 12) and the aqueous latex of fluorine mentioned in Example 13 made of elastomers. This mixture (20 ml) was added dropwise to a bath containing 1.5% SiO ₂ and 2.1% CaCl ₂ and 94 ml of the 0.2 mentioned in Example 3 from 100 ml of 0.5 molar aqueous silica % strength aqueous trimethylnonanol ether and 6 ml 50% aqueous CaCl ₂ had been prepared. The resulting pellets were washed with water and then _{dried first in air and then over P 2} Os under reduced pressure at room temperature. The pellets obtained from the elastomer mix were non-sticky and pourable.

Example 15

422 ml sodium silicate solution (quality F, manufactured from the applicant, SiOjZNa ₂ O ratio 3.25,

Na ₂ O = 8.7%. SiO ₂ = 28.4%, viscosity

(68 ⁰ C) = 16OcPs. specific gravity 1.386) diluted to 4 l with distilled water. This solution

was passed through the cation exchange column described in Example 5 in the acid form. A bath containing 0.5% S1O2 and 7.6% NH ₄ Cl was converted into 1000 ml of 15% strength from 250 ml of the 0.69 molar silica solution obtained NH ₄ Cl, 250 ml of distilled water and 500 ml of a 0.05% strength aqueous solution of the trimethylnonanol ether described in Example 3 were prepared. 200 m! No. 2 polychloroprene latex (37% solids, pH ICS) added dropwise. The resulting pellets were held in the bath for 30 minutes. The bath was decanted and the pellets were washed three times with 21% water each time. The pellets were dried in the air at room temperature and normal pressure. The product obtained was non-sticky and free-flowing.

Example 16

A bath was made with a buffer added to counteract the rise in pH associated with the addition of the alkaline polychoprene a * sx. The buffer was prepared by diluting a mixture of 1.75 ml of 2 molar HCl, 0.1 g of the trimethylnonanol ether mentioned in Example 3 and 12.60 ml of 2 molar glycine solution with distilled water to 50 ml. The buffer was then added to 100 ml of 0.69 molar silica (prepared in the manner described in Example 15) and 50 ml of 30% aqueous NH ₄ Cl. 20 ml of No. 2 polychloroprene latex (37% solids, pH 123) was added dropwise to the bath. The pH of the bath increased from 335 to 3.55 compared to an increase to 6.8 for the same but nk-ht buffered bath. 80 ml of the latex could be added to the powdered bath before the pH rose above 6.0. At this pH value, the bath gel formed rapidly

Example 17

A bath containing 2.0% SiO ₂ and 7.9% NH ₄ Cl was contained in 1000 ml of 0.69 molar acid (prepared as described in Example 15 method), 500 ml 30% NH ₄ CI and 500 ml of a 0.2% strength aqueous solution of the trimethylnonanol ether mentioned in Example 3 was prepared. 200 ml of polychloroprene latex No. 3 (33% solids, pH 12) was brought from pH 12.0 to pH 12.5 by the addition of 1N NaOH. This latex was added dropwise to the bath. The resulting pellets were washed with water and then freeze-dried at -178 ° C under high vacuum. At room temperature the dried pellets were non-sticky and free flowing.

Example 18

heptadecyl sulfate (anion-active surfactant), 80 ml of 15% aqueous NH ₄ Cl and 4 ml of the above-described silica sol modified with aluminum oxide. To this bath, 20 ml of polychloroprene latex No. 2 (37% solids, pH 12 ^) was added dropwise. The drops coagulated and the coated pellets formed were washed and dried. Non-sticky, free-flowing pellets were obtained.

Example 19

A bath containing 1.0% SiO ₂ and 8.0% AlCl ₃ was made from 5 ml of 0.69 molar aqueous silica (prepared in the manner described in Example 15), 9 ml

30% aqueous AlCl ₃ · 6 H ₂ 0.5 ml of a 0.2% aqueous solution of the trimethylnonanol ether mentioned in Example 3 and 1 ml of distilled water were prepared. 2 ml of polychloroprene latex No. 2 (37% solids, pH 12 , 5) added dropwise The drops coagulated and were taken out of the bath, washed and dried non-sticky, free-flowing pellets are obtained.

Examples 20-23

Four baths were each made of 2.5 ml of 0.69 molar aqueous silica (prepared in the manner described in Example 15), 5 ml of a 0.5% aqueous solution Solution of the trimethylnonanol ether mentioned in Example 3 and 123 ml of a 30% aqueous solution of the the following salts are produced:

Example 20 NH ₄ Br Example 21 (NH ₄ J ₂ HC ₆ H ₅ O ₇ (CiIrBt) Example 22 (NH ₄ J ₂ Cr ₂ O ₇ Example 23 NH ₄ SCN

Mi each bath were then added dropwise 2 ml polychloroprene no. 2 (37% solids, pH 12.5). The elastomer pellets thus formed were washed separately with water and dried. In all cases, non-sticky, free flowing pellets were obtained.

45

Example 24

A bath was made using an alumina modified silica sol. This product is an acidic, aqueous dispersion containing 30% solids of positively charged colloidal particles, which consist of a dense silica and a shell of positively charged polymeric aluminum oxide. It has the following approximate chemical composition: 26% SiO ₂ , 4.0% Al ₂ Oj, 1.4% Cl, 0.2% MgO, viscosity 5 to 15 cPs at 25 ° C, pH (25 ° C) 4 J to 4.5, approximate particle diameter 16 μm, specific weight (25 ° C.) 1.23.

The bath, which contained 0.7% SiO ₂ / Al ₂ O ₃ and 6.1% NH ₄ CI, consisted of 116 ml of 0.2% aqueous sodium To 90 ml of # 2 polychloroprene latex (37% solids, pH 12.5) was added 10 ml of naphthenic extender oil. The mixture was shaken vigorously to form an emulsion. A bath containing 1.0% SiO ₂ and 7.6% NH ₄ CI was made from 50 ml of 0.69 molar silica (prepared in the manner described in Example 15), 100 ml of 15% aqueous NH ₄ CI and 50 ml of a 0.05% strength aqueous solution of the trimethylnonanol ether mentioned in Example 3 were prepared. The polymer latex stretched with the oil was added dropwise to the bath. The pellets formed in this way were separated from the bath, washed with water and dried, giving non-sticky, free-flowing pellets of the elastomer extended with the oil.

Example 25

A bath containing 0.9% SiO ₂ and 10.0% NaCl was made 0.35 molar by dissolving 100 g NaCl in 900 g

aqueous silica, dissolving 100 g of NaCl in 900 g of an 0.05% aqueous solution of that mentioned in Example 3 Trimethylnonanolether and adding both solutions together. The bath was prepared by adding of 1 N HCl during the dropwise addition of 200 ml polychloroprene latex No. 2 (37% solids, pH 1Z5) kept at pH 4 to 4.5. The here formed Pellets were kept in the bath for 16 hours, then washed with water and dried, using non-sticky, free-flowing pellets of the non-crosslinked elastomer were obtained.

Example 26

A bath containing 13% SiO ₂ , 33% NH ₄ Cl and 11.1% NaCl was made by mixing 25 ml of 0.69 molar silica (prepared in the manner described in Example 15), 10 ml of 30% NH ₄ Ci in a 0.2% aqueous solution of the trimethylnonanol ether mentioned in Example 3 and 40 ml of 20% NaCl in a 0.2% aqueous solution of the trimethylnonanol ether mentioned in Example 3 and 125 ml of distilled water. The bath was adjusted to pH 5.0 with 1N NaOH. To the bath was added dropwise 20 ml of No. 2 polychloroprene latex (37% solids, pH 12.5) while it was maintained at pH 5.0 by the dropwise addition of 1N HCl. The pellets formed in this way were taken out of the bath after one hour, washed three times with 500 ml of distilled water each time and air-dried, non-sticky, free-flowing pellets being obtained.

Example 27

35

A bath. which contained 0.5% chlorohydrol (polymeric aluminum chlorohydroxide complex with 47.0% Al2O3 and 163% chloride) and 23% CaCl ₂ , was obtained by mixing 10 ml of 10% aqueous chlorohydrol and 175 ml of a 0.05% aqueous solution of the trimethylnonanol ether mentioned in Example 3 and 15 ml of 25% strength aqueous CaCl ₂ . The solution was adjusted to pH 5.0 with 1N NaOH. While 20 ml of No. 2 polychloroprene latex (37% solids, pH 12.5) was added dropwise, the bath was gently stirred and heated to pH 5.0 by adding 1 Ji-HCl dropwise. The pellets were kept in the bath for one hour and then washed three times with 250 ml of distilled water each time. The pellets were then air-dried to form free-flowing, non-sticky elastomer particles.

Example 28

A surfactant-free bath containing 1.0% SiO ₂ and 7.6% NH ₄ Cl was distilled from 100 ml 0.69 molar aqueous silica (prepared according to Example 15), 200 ml 15% aqueous NH 4 Cl and 100 ml Water produced. A 100 ml measuring cylinder was filled with this bath. From a 10 ml syringe fitted with a size 20 needle, No. 2 polychloroprene latex (37% solids, pH 12.5) was applied as a continuous stream to the surface of the bath on one side of the graduated cylinder, with a small one Pool was formed. By grasping the edge of the pool with tweezers on the other side of the measuring cylinder, a loose fiber made of coagulated polychloroprene coated with water-containing silica was pulled off. The fiber was washed and air dried and was then non-sticky.

Example 2S

The experiment described in Example 28 was repeated, however, more force was applied to the syringe, causing the stream of latex to hit the surface of the Bath penetrated. The weight of the coagulating stream pulled him to the bottom of the bath, where a non-sticky, endless thread of elastomer ran from 1 to 2 mm in diameter piled up.

Example 30

The experiment described in Example 29 was repeated, however, after penetrating the interface at the surface of the bath through the Latex flow the force exerted on the syringe was reduced and adjusted so that the droplets came out of the Needle fell into the bathroom. The resulting pellets were non-sticky and pourable after washing and drying.

Example 31
Part A

To 200 ml of a 30% solids aqueous colloidal sol of alumina modified Silica from pH 8.6 to 93, prepared according to Example 18 were stirred in one Add 2.0 ml of concentrated HCL (38%) to the mixer. The resulting colloidal solution that is 29% solids contained, had a pH of 3.0.

part B

A modified polychloroprene latex was prepared by adding 10 ml of a 1% strength aqueous solution of Mydroxyethyl cellulose (average MW 30,000 D) of 90 ml # 2 polychloroprene latex (37% solids, pH 12.5) was added. The emulsion was constantly stirred to Avoid creaming.

Part C.

A bath. which contained 4.3% SiO ₂ / Al ₂ O ₃ and 74% NH ₄ Cl, was obtained by mixing 2.5 ml of the colloidal silica solution prepared according to Part A, 10.0 ml of 15% aqueous NH ₄ Cl, 1 ml a 0.2% aqueous solution of an amphoteric fluorinated surfactant. 5 ml of the modified polychloroprene latex prepared according to Part B were added dropwise to this bath. The resulting pellets were separated from the bath, washed with water and dried, giving non-sticky, free-flowing, essentially spherical pellets of modified polychloroprene.

Example 32

A bath containing 0.5% SiO ₂ , 7.6% NH ₄ CL and 0.01% AlCl 3 was made 1000 by mixing 250 ml of 0.69 molar silica (prepared according to Example 15 and aged 2 days) ml of 15% aqueous NH ₄ Cl, 200 ml of water, 500 ml of a 0.05% aqueous solution of the trimethylnon mentioned in Example 3

anol ethers and 50 ml 10% aqueous AlCl ₃ · 6 H2O, which had been adjusted to pH 5 with 1N NaOH. This bath was made by adding 1N HCl while adding 200 ml of polychloroprene latex No. 2 (37% solids, pH 12.5) dropwise which required 8 minutes and an additional hour at pH 4.5-5.0 held. The drops that coagulate were separated from the bath, washed three times with water, placed in water for 3 hours, and then air dried. The pellets obtained were non-sticky and free-flowing.

Example 33

A silica sol. which contained 4.6% solids and had a pH of 5.0 was prepared by adding 265 ml of a 15% solids aqueous silica sol (pH 10.5) dropwise with vigorous stirring to a solution of 70 iti! i ii-HCl in 535 rn! Water was given. A bath containing 0.6% SiO ₂ . 7.6% NH ₄ CL and 0.013% AiCl ₃ was obtained by mixing 250 ml! of the above-mentioned sol, 1000 ml of 15% aqueous NH ₄ Cl, 700 ml of a 0.03% aqueous solution of an amphoteric fluorinated surfactant and 50 ml of 1% aqueous AlCl ₃ · 6 H ₂ O, which is diluted with 1N NaOH adjusted to pH 5.0. The bath obtained had a pH of 4.3. This bath was stirred and maintained at pH 4.5-5.0 by the addition of HCl during the dropwise addition of 200 ml No. 2 polychloroprene latex (37% solids, pH 12.5). The pellets formed were stirred in the bath for one hour, separated off, washed three times with water and soaked in 2 l of water. After drying, the pellets were non-sticky and showed little tendency to agglomerate.

Example! 34

In the manner described in Example 33, 42 ml of an aqueous colloidal silica sol containing 49% solids (pH 8.9, particle diameter 220 to 250 Å) were mixed with 3.9 ml of n-HCl and 454 ml of water, an aqueous sol with 5.6% SiO _{2 was} obtained. A bath containing 0.7 SiO ₂ , 7.6% NH ₄ Cl and 0.013% AlCl ₃ was prepared by using 250 ml of the above sol in place of the sol used in Example 33 and adding 1N- HCl were kept at pH 5.0. The remaining working steps of the experiment described in Example 33 were then repeated, non-sticky, free-flowing elastomer pellets being obtained.

Example 35

In the manner described in Example 33, 125 ml of a 30% solids aqueous colloidal Kiese' ^ rdesols (pH 9.9) mixed in 125 ml of distilled water with 28 ml of 1N HCl and 637 ml of water A bath was made using 250 ml of this sol in place of the sol used in Example 33, whereupon the remaining steps of the experiment described in Example 33 were repeated. Non-sticky, free-flowing pellets were obtained in this way.

Example 36

To 400 ml of a 30% solids aqueous colloidal sol of alumina modified silica having a pH of 8.9 was added 4.0 ml of concentrated (38%) hydrochloric acid with vigorous stirring. The sol obtained has a pH of 3.0 and a solids content of 29.7%. A bath containing 43% SiO ₂ and 7.5% NH ₄ CI was made from 250 ml of this sol, 1000 ml of 15% aqueous NH ₄ CI. 650 ml of water and 100 ml of a 0.2% strength aqueous solution of an amphoteric fluorinated surfactant were prepared. The bath had a pH of 3.7 and was kept below pH 4.5 by adding 0.1 N HCl during the dropwise addition of 200 ml of polychloroprene latex No. 2 (39% solids, pH 12.5). The droplets coagulated and were stirred in the bath for 30 minutes, separated, washed three times with water and dried in WC to give non-sticky pellets.

Example 37

A bath containing 1.5% SiO ₂ and 7.6% NH ₄ Cl was made by mixing 100 ml of 0.69 molar aqueous silica (prepared according to Example 15), 94 ml of a 0.2% solution of the trimethylnonanol ether mentioned in Example 3 in ethanol and 6 ml of a 50% aqueous solution of CaCl ₂ · 2 H ₂ O prepared. To this bath was added dropwise 20 ml of a 40% solids butadiene-acrylonitrile copolymer latex having a pH of 8.0. The coagulated droplets were stirred for one hour in the bath, separated, and dried under reduced pressure at 6O ⁰ C .: wherein perfectly round balls, non-tacky and free flowing warer., Were obtained.

Example 38

A latex mixture was made from 100 ml polychloroprene latex No. 2 (37% solids, pH 123) and 60 ml TSC natural rubber latex (62% solids). The resulting mixture was adjusted by adding 1 N NaOH to pH 1 22nd A bath was made in the manner described in Example 37, but on a 10 times larger scale. While the latex mixture was added dropwise to the bath, the bath was maintained at pH 5.0 by adding 1N HCl. The coagulated drops remained in the bath for one hour. They were then separated off, washed three times with water and dried first in air for 5 hours and then under reduced pressure over P ₂ O ₅ at room temperature for 3 days. The coated pellets of the polychloroprene rubber were non-sticky and pourable.

Example 39

A bath containing 0.7% SiO ₂ Zal ₂ O ₃ and 7.6% NH ₄ CI contained, was prepared by mixing 40 ml of a positive alumina modified silica sol (Example 18), 1000 ml of 15% aqueous NH ₄ Cl and 960 ml of 0.05% aqueous sodium lauryl sulfate. The bath had a pH of 4.9 and was made by adding 1N HC during the dropwise addition of 200 ml ! Maintained at pH 5.0. The coagulated drops were stirred in the bath for one hour, washed with water and air-dried, giving non-sticky, free-flowing pellets.

Example 40

A bath. which contained 0.1% chlorohydrol and 7.6% NH ₄ CI, was obtained by mixing 1000 ml of 15% aqueous NH ₄ CI, 980 ml of 0.1% aqueous sodium lauryl sulfate and 20 ml of 10% hydrochloride! (47.0% Al ₂ O ₃ , 163% chloride). To the bath,? 00 ml of No. 4 polychloroprene latex was added dropwise while it was kept at pH 6.5 by the addition of 1N HCl. After the addition, the pellets were stirred in the bath for one hour, washed with water and air-dried. The non-crosslinked pellets of the elastomer were non-sticky and free flowing.

Example 41

In container 1 that shown in FIGS. 1 and 2 Apparatus, the following aqueous solutions were mixed:

10,000 ml of 15% aqueous ammonium chloride
9 500 ml 0.03% aqueous surface-active sodium lauryl sulfate

500 ml of 30% solids colloidal alumina modified silica sol (Example 18).

The bath produced in this way had a pH of 5.4 and contained 0.9% SiO ₂ and 7.6% NH ₄ Cl. With stirring, 3480 g of a 40% solids polychloroprene latex, prepared in the same manner as No. 2 polychloroprene latex, was added through the capillary tubes over 13 minutes. At the same time, the pH of the bath was kept at 5.4 by gradually adding 51 ml of 1η hydrochloric acid. Immediately after the addition of the latex, which took 13 minutes, stirring was continued for 17 minutes without further addition of acid. During this time the pH of the bath rose to 6.6. During this 17 minute period, the agitation kept the particles in suspension. The stirrer was then turned off and the particles settled. The supernatant liquid was separated from the particles by decantation.

The particles were washed by adding 8000 ml of distilled water and stirring for 5 minutes became. The stirrer was then switched off and the supernatant liquid by decanting from the Particles separated. This washing was repeated twice. The particles were allowed to air dry left up to a constant weight of 1315 g. They were pourable and non-sticky.

Example 42

Using the methods shown in FIG. 1 and F i g. 2 was a bath by mixing the device shown the following aqueous solutions prepared in container 1:

10,000 ml of 15% aqueous ammonium chloride
9,950 ml of 0.03% aqueous surface-active sodium lauryl sulfate

50 ml of one modified with polymeric aluminum acid aqueous colloidal silica sol

The modified silica sol was prepared by slowly adding 500 g of a 35% strength aqueous solution of basic aluminum _{acetate stabilized with boric acid to 400 g of aqueous colloidal silica sol (30% SiO 2} , mean particle size 7 τημ, SiO ₂ / Na ₂ O weight ratio 50, pH Value (25 ⁰ C) 9.9, freezing point 0 ⁰ C) were placed in a mixer and the mixture was filtered through coarse filter paper to remove the small amount of gel. The bath produced in this way had a pH of 5.3 and contained 0.1% colloidal silica sol which was coated with polyaluminum acid and 7.6% NH ₄ Cl.

ίο With stirring, 3590 g of a 40% solids containing polychloroprene latex produced in the same manner as polychloroprene latex No. 1 had been. added to the bath through the capillary tubes within 9 minutes. During this time it rose the pH of the bath to 6.7. With continued stirring, the particles remained in suspension for an additional 51 minutes held, with no significant change in the pH of the bath occurred. The stirrer was switched off whereupon the particles settle. The supernatant liquid was removed by decanting from the particles severed.

The particles were made by adding 8000 ml of distilled water and then stirring for 10 Minutes washed. The stirrer was then switched off and the supernatant liquid by decanting separated from the particles. This washing was repeated three times. The particles were drying out left to the air up to a constant weight of 1446 g. They were pourable and non-sticky.

Example 43

Using that shown in Fig. 1 and Fig.2 Apparatus, the following aqueous solutions were mixed in container 1:

10,000 ml of 15% aqueous ammonium chloride,
9,950 mi Ö, Ö3% / biges aqueous surface-active Na-

trium lauryl sulfate

50 ml of that described in Example 42 with polyaluminic acid modified aqueous collo: dalen silica sol

The bath prepared in this way had a pH

■ 45 value of 5.2. With stirring, 4578 g of one in the 40% solids polychloroprene latex made in the same manner as No. 2 polychloroprene latex added through the capillary tubes within 18 minutes. During this time the pH increased

so on 6.7. With continued stirring, the particles were held in suspension for an additional 42 minutes, with none significant change in the pH of the bath occurred. After turning off the stirrer, the particles were left The supernatant liquid was separated from the particles by decantation.

The particles were made by adding 20,000 ml

distilled water followed by stirring for 10 minutes. The stirrer was turned off and the supernatant liquid separated from the particles by decantation. This washing was repeated The particles were air dried up left to the constant weight of 1767 g. They were free flowing and non-sticky.

Example 44

A bath containing 0.6% SiO ₂ , 03% CaCl ₂ , 03% AlCl ₃ and 0.6% NaCl was made by mixing 1694 g

25th

• SJ H ₂ O, 10.0 g AICI ₃ · 6 H ₂ O. 24.2 g CaCl ₂ · 2 H ₂ O, 12.0 g

5j NaCl, 1.2 g of an amphoteric fluorinated surfactant and

iij 250 mg of a colloidal silica sol prepared that

ρ? had a pH of 2.0 and contained 4.8% SiO ₂ .

Jj This colloidal sol had been made by a

A mixture of 125 ml of one containing 30% solids

|| aqueous silica sol and 125 ml of water in one

y running mixer was added containing 637 ml of water

I and 40 ml of 1 n-I-ÄCI.

198 ml of one in the

jjj in the same way as the polychloroprene latex No. 1

?] provided, 40% solids containing polychloro-

'" added prenlatex. After 30 minutes the bath was turned off

i decanted from the pellets that have now formed. the

^; j pellets were kept in 2 l of water for 30 minutes, from

,, Wash water filtered off and 2 minutes in a basket

F centrifuge spun. The pellets were then using

4 talcum powder in an amount that is 1.5% by weight

';! the pellet matched, shaken and allowed to air dry

Spread out in a dish overnight. they were

I then through P ₂ Os under reduced pressure

jj room temperature dried. The

y non-sticky, free-flowing pellets contained 1.56 ml

I equivalent residual alkalinity per 100 g of the isolated

I polymer as determined by non-aqueous titration

% up to the transition point of bromophenol.

ν, B e i s ρ i e I 45

$ A bath containing 0.5% SiO ₂ , 0.9% CaCl ₂ and 0.3% AlCl ₃

% was made by mixing 1714.6 ml of H ₂ 0.10.0 g

I AlCl ₃ 6 H ₂ O, 24.4 g CaCl ₂ ■ 2 H ₂ O, 1.2 g of the

I play 3 named trimethylnonanol ether and 250 ml

H 0.69 molar silica, which overcomes 5 days of aging

, $ had been made. That bath were

Γ; 5 dropwise 200 ml of one in the same way as that

| * j No. 1 polychloroprene latex made, 40% solids

containing rölychlöropreriiatex zugesetzi. The one here The resulting pellets were isolated, washed and dried in the manner described in Example 44. The free-flowing, non-sticky pellets obtained in this way had a residual alkalinity of 2.43 milliequivalents 100 g.

B e i s ρ i e 1 46

A latex mixture was prepared from 2 ml of the sodium silicate solution described in Example 15, 15 ml of In-NaOH and 198 ml of the 40% solids polychloroprene latex prepared in the same manner as No. 2 polychloroprene latex. This mixture was added dropwise to a bath containing 1.8% CaCl ₂ , 1.7% NaCl, 0.6% AlCl ₃ and 0.6% modified sol made from 898.6 ml of water, 1000 ml of 2% AlCl ₃ . 6 H ₂ O (adjusted to pH 3.5 with 1N NaOH), 36.4 g of anhydrous CaCl ₂ , 34 g of NaCl, 1.0 g of 30% strength sodium lauryl sulfate and 30 ml of the modified aqueous colloidal described in Example 42 Silica sol had been produced. The pellets formed in this way were removed from the bath after 15 minutes and washed with water in the manner described in Example 44, centrifuged, treated with talc and dried. The pellets obtained were non-sticky and free-flowing.

In addition 2 Biatt drawings

Claims (2)

Patent claims: 1. Non-sticky, elastomeric molded parts that consist of a normally tacky, non-crosslinked elastomers and, based on the total weight of the Moldings, less than 3% by weight water-soluble Material, less than 1% by weight of volatile material, optionally customary additives, and 0.05 to 3% by weight of a cohesive, uniform, porous coating made of a water-insoluble, hydrous inorganic oxide from the silicic acid and aluminum acid polymers, silicic acid-aluminum acid copolymers and their mixtures exist and have a smallest dimension of 0.01 to 10 mm. 2. Process for the production of non-sticky, elastomeric molded parts according to claim 1, characterized in that a latex is used a normally tacky, uncrosslinked elastomer with a solids content of 20 to 65% by weight in the form of drops or a regulated stream in contact with an aqueous bath brings that, based on the total weight of the bath a) 04 to 25% by weight of a soluble coagulating salt for the latex, and b) 0.01 to 5 wt .-% of a soluble or colloidally dispersed, water-containing inorganic Oxides from silicic acid polymers, aluminum acid polymers, silicic acid-alurcinic acid copolymers or mixtures thereof contains and has a pH of 2 to 7, so that if a drop of 1.0 n — NaOH is added to the bath becomes, the drop immediately from a cloudy coating of gelled, water-containing inorganic. Oxide is surrounded, the latex or the bath may contain customary additives, and you thereby the. Latex coagulates and is highly porous, with the water-containing one which is insoluble in water Inorganic oxide coated moldings of the coagulated elastomer that one forms Separates molded parts and removes water-soluble and volatile substances from them. The invention relates to non-tacky molded parts made from normally tacky elastomers and to a method for their manufacture. It is known to emulsify polymerizable monomers in water and then to disperse them in polymers Convert form. The dispersions formed in this way are referred to as latices. Natural rubber also occurs in latex form. Some latices are very useful as they are formed, z. B. as a base for latex paints. For other applications it is necessary to coagulate the polymer and separate from the latex. The most important technical form for these polymers is the form of washed and dried, non-sticky molded parts. These moldings need to be washed up they contain less than 3% by weight of water-soluble material and are then dried until they are less than Contain% volatile matter by weight. If the coagulated polymer is inherently tacky, the polymer can be easily removed from the Isolate the aqueous phase, wash and dry, whereby it forms a free-flowing, free-flowing powder that is Can be easily handled during further processing If, however, the polymer is inherently sticky, the polymer is obtained as an agglomerated mass by coagulation of the latex, which is difficult to get through Washing rid of impurities and also ίο difficult to dissolve, mix with other substances and in compounding, vulcanizing and shaping difficult to feed In the field of natural rubber and synthetic rubber, your problem of agglomeration of f5 normally sticky polymers before vulcanization Much attention paid to Some viable solutions have been found. The US-PS 28 79 173 describes a method for coagulating eiens polychloroprene latex by suspending drops in a volatile, water-immiscible organic liquid in which the polychloroprene latex is insoluble, while the liquid is kept at a temperature below -20 ⁰ C, until the drops are completely frozen and coagulated. The frozen drops or pellets obtained are separated off and given a 5 in the still frozen state to 20% by weight of an inert powder, e.g. B. talc, coated so that they do not stick together when they thawed and dried. However, the application of this method is due to the cost of recovery the organic liquid, the energy costs of freezing and the undesirable heavy loading limited with inert material. There is still a need for something more practical, more functional and economical process for the production of non-sticky, washed and dried molded parts of normally sticky elastomers. US Pat. No. 3,053,824 describes the coagulation of an elastomer latex buffered with a phosphate or borate by introducing the Laiex into an aqueous aluminum or titanium salt solution, which also contains an alkali or alkaline earth salt. The patent states that the coagulated particles formed do not stick together before washing them to remove the coagulating salts. An indication There is no mention of the stickiness of the particles after washing. The US-PS 38 46 365 describes a powdered, filled polymer, which by joint emulsification a dilute solution of an elastomer and a solid, finely divided filler for the elastomer in a volatile organic solvent, introducing the emulsion into an aqueous alkali silicate solution at a pH preferably 7 to 12 and evaporation of the organic solvent is produced. This creates a finely divided, non-sticky coprecipitate of latex and silica residue. It is found that condensation of the silicate anions is to be avoided. The invention is based on the finding that non-sticky, unvulcanized, washed and dried elastomeric molded parts made from a latex normally tacky elastomers can be made by a simple and inexpensive process. The invention makes non-sticky, elastomeric molded parts available that normally consist of a sticky, unvulcanized elastomers and. based on the total weight of the molded part, less than